This invention relates to polyether-polycarbonate copolymers. More particularly, the invention relates to poly(aryl ether)-poly(aryl carbonate) block copolymers and to the preparation of such block copolymers.
Polycarbonates are well-known commercially available resinous materials having a variety of applications. They are typically prepared by the reaction of dihydroxy compounds and a carbonate precursor, such as phosgene. The polycarbonates are high temperature, high performance thermoplastic engineering polymers with a good combination of thermal and mechanical properties, especially when the polymer is prepared from one or more aromatic diols. However, the polycarbonates do exhibit poor hydrolytic stability, particularly when exposed to humid environments for prolonged times and/or elevated temperatures and poor solvent resistance.
Attempts to modify the properties of polycarbonate resins by blending with other polymeric materials are quite often unsatisfactory because of the incompatibility of the polycarbonates with other resinous materials. To overcome these problems, it has been proposed to polymerize other resinous materials into the polycarbonate molecule. Thus, random, block and graft copolymers of polycarbonates and other polymers, such as polyethers, are known. For example, polyether sulfone has been interpolymerized into the polycarbonate molecule by (1) preparing a hydroxyl-terminated polyether sulfone and condensing the hydroxyl-terminated polysulfone oligomer with 2,2-bis-(4-hydroxyphenyl)propane (Bisphenol A) and phosgene in the presence of pyridine; (2) performing both a hydroxyl-terminated polyether sulfone oligomer and a Bisphenol A-polycarbonate oligomer and extending the oligomers to a high molecular weight by phosgenation in a common solvent; and (3) by the pyridine-catalyzed reaction of chloroformate-terminated polycarbonate oligomers with hydroxyl-terminated polyether sulfone oligomers in a common solvent. In each of these methods, a carbonate radical is linking the polycarbonate and polyether sulfone blocks.